Fuel injection nozzle



NOV. v, RQOSA FUEL INJECTION NOZZLE Filed July 12, 1967 A mmm s MEN. MM.1% PM. 1 m w .M m

, NM 6% W a j United States Patent 3,477,648 FUEL INJECTION NOZZLEVernon D. Roosa, West Hartford, Conn. (Hartford Machine Screw Co., P.O.Box 1440, Hartford, Conn.

' Filed July 12, 1967, Ser. No. 652,872 Int. Cl. B05b 1/32; F23k 5/00US. Cl. 239-533 1 Claim ABSTRACT OF THE DISCLOSURE This inventionrelates to fuel injection nozzles for internal combustion engines and isan improvement in the nozzle described in my prior Patent 3,224,684,issued Dec. 21, 1965, and entitled Fuel Injection Nozzle.

In fuel injection nozzles of the type contemplated by this invention,the valve is lifted from its seat against the bias of a spring by thepressure of the fuel delivered to the nozzle from an associated highpressure pump in measured quantities or charges. Each charge of fuel isdischarged from the nozzle into a combustion chamber of an associatedengine, and its discharge is timed to take place when the air in thecombustion chamber is compressed and continues after ignition of thefuel begins. The pressure of the charge must be substantially higherthan the pressure within the combustion chamber in order to dischargethe fuel during the short interval available for injection. This maypresent a problem at cranking speeds when the inherent leakage in thepump may be suflicient to reduce the pressure developed by the pump andhence the quantity of fuel delivered to the engine. Moreover,particularly under cold starting conditions, it is desirable to providefor early injection of at least part of the fuel into the cylinder tofacilitate the ignition thereof.

Accordingly, it is one object of this invention to provide for theinjection of a portion of the fuel into the engine prior to the openingof the nozzle valve. Included in this object is the provision of anozzle wherein the reverse flow of combustion gases into the nozzle isprevented.

Another object of this invention is to provide a nozzle which enhancesthe cold starting capabilities of the engme.

Another object of this invention is to provide a fuel injection nozzlewhich promotes an improved flame propagation during the combustion ofthe fuel.

A still further object of this invention is to provide a fuel injectionnozzle which delivers excess fuel for startmg.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

The invention accordingly consists in the features of construction,combination of elements and arrangement of parts which is exemplified inthe construction hereafter set forth, and the scope of the invention isindicated in the appended claims.

In the drawing:

FIG. 1 is a cross-sectional view of a portion of a fuel injection nozzleembodying the present invention in conice junction with a schematicillustration of an associated high pressure pump for deliveringmeasured. charges of fuel to the nozzle; and

FIG. 2 is a fragmentary cross-sectional view, similar to FIG. 1, of aportion of the fuel injection nozzle embodying a modified form of theinvention.

Referring to the drawing, in which like numerals refer to like partsthroughout the several views, the exemplary nozzles shown therein aregenerally similar to the nozzle illustrated in my aforementioned priorPatent 3,224,- 684 and includes an elongated generally tubular bodymember 10 having a nozzle tip 12 rigidly fixed at one end thereof and acentral longitudinal bore 14 extending throughout its length. Locatedwithin the central bore 14 is a rod-like plunger stem or valve 16 whichcooperates with a conical valve seat 18 formed in the nozzle tip 12 tocontrol the discharge of fuel from the nozzle body 10-. A valve guide 20fixedly positioned within the bore 14 of the body 10 at a positionremote from the valve seat 18 slidably mounts and aligns the valve 16 soas to permit rapid reciprocal movement thereof within the bore 14 underthe influence of the fuel pressure within the bore 14 against the biasof spring 22. The nozzle is provided with a fuel inlet 24 communicatingwith the bore 14 of the nozzle body 10 for delivery of high pressurefuel thereto adjacent the guide 20 from an associated high pressure fuelpump 26.

The upper end of the valve 16 is shown as being provided with apartispherical surface 25 which swivelly engages a spring seat 28 havinga complementary partispherical surface. The other end of the spring 22is shown as being similarly provided with. a spring seat 30 whichswivelly engages an annular washer 32 with the washer 32 and the springseat 30 providing complementary partispherical engaging surfaces toaccommodate lack of squareness of the ends of the spring 22 or axialmisalignment between the valve 16 and the annular washer 32.

The annular washer 32 is seated against the end of an externally andinternally threaded longitudinally slotted retaining sleeve 34 theexternal threads 35 of which are threadably received in the internalmating threads 36 of the tubular body 10.

The internal threads 38 of retaining sleeve 34 threadably receive anexternally threaded stop 40 to provide an adjustable lift stop for thevalve 16. With this arrangement, the nozzle valve opening pressure maybe adjusted as desired by merely turning the retaining sleeve 34 in orout until the desired biasing force is provided by the spring 22, andthe valve lift may be independently adjusted by axially adjusting thestop 40 with respect to the retaining sleeve 34. Lock nut 46 which isthreaded on the external threads 35 of the retainer sleeve 34 istightened against the end shoulder 48 of the tubular body 10 to maintainthe retaining sleeve 34 and the lift stop pin 40 in adjusted position.

The charge pump 26 illustrated schematically in FIG. 1 is of the typemore fully described in my prior Patent 3,204,622 issued Sept. 7, 1965and entitled Fuel Injection Pump Timing Device. For the purpose ofdescribing this invention it is suflicient to state that the pump 26includes a pair of pistons 50 which are reciprocated radially as therotor 52 is rotated in timed relation with the associated engine throughintermediate roller shoes 54 and rollers 56 which engage diametricallyopposed cam lobes 58 of relatively stationary cam 60 to pressurize themeasured quantity or charge of fuel within the chamber 62 of the chargepump. As more fully explained in the aforesaid Patent 3,240,622, thedelivery passage 64 of pump 26 registers with the rotor outlet passage65 from the charge pump chamber 62 to deliver the highly pressurizedmeasured charge of fuel to inlet 24 of the nozzle.

The pressurized fuel delivered to the inlet 24 by the charge pumpincreases the pressure of the fuel within the bore 14 and acts on theareas 66 and 68 of the valve 16. When the force exerted thereby issufircient to overcome the bias of spring 22 to move the valve 16upwardly, the charge of fuel is discharged through the orifices 11 inthe nozzle tip 12.

It will be apparent that at low cranking speeds the leakage past thepistons 50 and through the other clearances within the pump 26 duringthe pumping stroke will be greater than the leakage at higher speedsbecause of the greater interval of time required by the pumping stroke.Since the pressure within bore 14 must reach a predetermined level toovercome the pressure of the biasing spring 22 and open the valve 16 toinitiate the injection of fuel by the nozzle, it is apparent that atslow cranking speeds, the amount of fuel delivered by prior nozzles ascompared with the maximum capability of the pump is reduced. Since it isdesirable to provide a system having the capacity to deliver excess fuelfor starting, any reduction in the quantity of fuel delivered to theengine under starting conditions is considered detrimetnal to thestarting capabilities of the engine.

This invention provides a solution for this problem.

Referring to FIG. 1, a small opening 70 is provided in z the nozzle tip12. Opening 70 has a small diameter of, say, 6 mils (or approximately /2the diameter of the ports 11) and is spaced above the valve seat 18 soas to provide a bypass for the delivery of fuel by the nozzle when thevalve 16 is seated on the valve seat 18.

As the pressure of the nozzle increases as the rollers 56 of the pump 26move up the leading surface of the cam lobes 58, a minor amount of thefuel delivered by the charge pump is sprayed into the cylinder beforethe pressure of the fuel in the bore 14 is sufiicient to lift the valve16 from the valve seat. Desirably the opening 70 is indexed with respectto the cylinder so as to provide a spray into the center of the cylinderwhere it will cornbust more readily and serves to cause a more uniformignition of the main charge of fuel subsequently discharged throughports 11 of the nozzle tip 12 for more uniform flame propagationthroughout the charge within the cylinder thereby providing maximumpower.

As the pressure in bore 14 begins to drop, the pressure within the bore14 would normally fall very rapidly since very little restriction isoffered to the flow of fuel. With the combustion pressures within theassociated cylinder rising rapidly due to the combustion of the fuel inthe cylinder, it is apparent that the use of the opening 70 alone wouldpermit the reverse flow of combustion gases into the nozzle. To avoidthis undesirable result, this invention provides a hydraulic restrictioneffective to prevent the reverse flow of fuel from the chamber 14a asthe pressure therein decreases.

In the exemplary embodiment of FIG. 1, such a hydraulic restriction isprovided by the spring biased oneway check valve at the inlet 24 of thenozzle. As shown, the ball 72 is biased into engagement with the seat 74by light biasing spring 76 which is held in adjusted position by anexternally fluted stop 78 positioned in an intermediate coupling element79 serially disposed in sealed relation between the separable ends ofthe inlet 24 and the supply line 81. The stop 78 may be secured in thebore 82 of the intermediate coupling element 79 by a light press fitsince the only requirement for the spring 76 is to bias the ball 72lightly toward the seat 74. The stop 78 may be provided with an axialextension 84 disposed concentrically within the spring 76 to limit themovement of the ball 72 from the seat 74. It will be apparent that, asthe pressure within the delivery passage 64 of the pump reduces to causereverse flow of the fuel from the nozzle toward the passage 64, the ball72 is automatically seated to trap the fuel within the nozzle therebymaintaining the bore 14 of the nozzle filled with fuel and preventingthe entry of combustion gases through the opening 70 into the nozzle.

Referring now to FIG. 2, there is shown another embodiment of thisinvention wherein an annular one-Way valve 86 is provided to obstructthe reverse flow of fuel out of the chamber 14a adjacent the valve seat.The washer 86 is preferably formed of a resilient low surface frictionmaterial, such as neoprene, and is when assembled, in the form of atruncated cone to form a seal with valve 16 to prevent the reverse flowof fuel from the chamber 1411 while at the same time being expandableunder the influence of the pressure from the charge pump to permit thepassage of fuel toward the chamber 14a. The upper end 87 of the washer86 may be reinforced and secured to the nozzle body in any desiredmanner as, for example, by a sleeve 88 secured in the bore 14 by a pressfit and overlying the upper end 87 of the washer 86 in clampingrelationship. Furthermore, since the washer 86 engages the valve 16 witha sliding fit, it is apparent that the valve is free to reciprocate intoand out of engagement with the valve seat 18.

It will thus be seen that the washer 86 will expand to allow fuel flowtoward the chamber 14a but will be automatically held in tight sealingrelationship by the pressure in the bore 14 and the chamber 14a toobstruct the reverse flow of fuel from chamber 14a, thereby maintainingchamber 14a full of liquid fuel and preventing the entry combustiongases.

From the foregoing it will be apparent that the invention provides afuel nozzle which will permit the preinjection of a desiredpredetermined portion of the fuel charge into the cylinder understarting conditions to obtain the attendant advantages set forth.

As will be apparent to persons skilled in the art, various modificationsand adaptations of the structure of the above described will becomereadily apparent without departure from the spirit and scope of theinvention, the scope of which is defined in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A fuel injection nozzle for delivering to the combustion chamber ofan associated engine pulsed fuel charges received from a high pressurefuel source comprising a nozzle body having a valve seat and a dischargetip at one end projecting into the combustion chamber of the associatedengine, an inwardly opening pressure actuated valve having a stemdisposed in said nozzle body and spaced therefrom to define an annularpassage, guide means mounting said valve for reciprocating movementtoward and away from the valve seat, an inlet conduit for deliveringfuel to a chamber adjacent the valve seat through said annular passageand a one-way valve disposed in said annular passage to oppose thereverse flow of fuel toward said inlet conduit said one-way valvecomprising a truncated conical washer secured in the passage toaccommodate reciprocation of the valve relative thereto, the washerbeing formed of a resilient material and having its smaller diameterdownstream relative to the flow of fuel from said inlet to said chamberto accommodate the forward flow of fuel therebetween. 60

References Cited UNITED STATES PATENTS EVERETT W. KIRBY, PrimaryExaminer US. Cl. X.R.

